1. Acids/ Bases
Assign.# 13.4

2. Neutralization Reactions
Recall, one of the most common types of reactions are acid/base reactions or neutralization reactions
We have various definitions of acids and bases, but they all react with characteristic properties.
NOTE – We will review some of the material from last year, but it is expected that you study all material previously taught.

3. Arrhenius Acid/Base
Arrhenius’ theory of acids/bases focuses on what molecules contain
An Arrhenius acid contains a H+
An Arrhenius base contains an OH-

4. Bronsted – Lowry Acid/Base
When Arrhenius’ definition covers many acids/bases, acid/base reactions are not about containing H+ or OH-
A Bronsted-Lowry acid is any compound that gives H+ during the reaction
A Bronsted-Lowry base is any compound that accepts H+ during the reaction.
We will use this definition most of the time in this class

5. Lewis Acid/Base
Ultimately, acid/base reactions are not about H+, but about the accepting or donating of electron pairs.
A Lewis acid is an electron pair acceptor
A Lewis base is an electron pair donor
Every acid/base in the previous two categories are also acids/bases in this category
Broadest definition

6. Class Example
Identify the acid/base as Arrhenius, Bronsted – Lowry, and/or Lewis:

7. Table Talk
Identify the acid/base as Arrhenius, Bronsted – Lowry, and/or Lewis:

8. Strong vs. Weak Acid/Base
Acids/Bases can be classified as strong or weak based on how much it disassociates.
Disassociate – To break apart
Acids/Bases that completely dissociate are called strong acids/bases
Acids/Bases that only partially dissociate are called weak acids/bases. These are in equilibrium with one another

9. Dissociation

10. Strong Acids/Strong Bases to Memorize
LiOH
NaOH
KOH
RbOH
CsOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
HBr
HCl HI
HNO3
H2SO4
HClO3
HClO4

11. I. pH The pH scale is 0-14. Acid = pH 0-7 Neutral chemicals = pH of 7.
The concentrations of acids and bases are often very low.
We use the pH scale to convey the concentration of H+
The pH scale is 0-14.
Acid = pH 0-7
Base = pH 7-14
Neutral chemicals = pH of 7.

13. pH/pOH We calculate the pH by: pH=-log([H+]) We calculate pOH by:
pOH=-log([OH-])
For strong acids and bases, the concentration of the compound is the [H+] or [OH-]
For bases, we only know [OH-], so we need to first calculate pOH and then convert to pH using the equation:
pH = 14 – pOH

14. Class Example
What is the pH of a M solution of NaOH?

15. Table Talk
What is the pH of a M solution of HNO3?

16. Conjugate Acid/Base Pairs
As with any reaction, there is a forward and reverse reaction for acid/base reactions.
Consider the following example:
HX + H2O H3O+ + X-
In the forward reaction HX is the acid because it donates H+ and H2O is the base because it accepts H+.
In the reverse reaction, H3O+ is now the acid and X- is now the base.
The pair of HX and X- are known as an conjugate acid-base pair ⇌

17. Conjugate Acid/Base Pairs
Every acid has a conjugate base that is formed when a proton (H+) is removed
Every base has a conjugate acid that forms when a proton is added

18. Class Example
Identify the acid, base, conjugate acid, and conjugate base in the following reaction. Identify the acid/base as Arrhenius, Bronsted – Lowry, and/or Lewis:
NH3 + H2O  NH4+ + OH-

19. Table Talk
Identify the acid, base, conjugate acid, and conjugate base in the following reaction. Identify the acid/base as Arrhenius, Bronsted – Lowry, and/or Lewis:
HSO3- + H2O  SO32- + H3O+